Former Mexican President Vicente Fox dropped the "F-bomb" for the second time in two days when discussing presidential front-runner Donald Trump's proposed border wall — this time, it was on live TV, CNN reports.

"I have to say that we are not, I am not going to pay for that f****** wall," Fox said during a live interview with Maria Bartiromo on Fox Business Network on Friday morning, repeating the phrase that resulted in Trump taking to Twitter on Thursday demanding an apology from the former Mexican president.

"I am not going to apologize," continued Fox to a visibly stunned Bartiromo.

Building a wall along the border and making Mexico pay for it has been a hot-button topic since Trump has been on the campaign trail. And, CNN notes that the idea has even "turned into a call-and-response at his rallies, where he asks supporters who will pay for the wall and they yell back, 'Mexico!'"

Fox, 73, who served as Mexico's president from 2000 to 2006, told the Fusion television network on Thursday that Mexicans were not paying for the wall that Trump repeatedly touts in his platform for the presidential nomination.

Fox has a history of making controversial statements. In 2005 he came under heavy fire from the Rev. Jesse Jackson and other African-American leaders for saying that Mexican illegals in the United States take jobs "that not even blacks want to do."

Former Mexican President Vicente Fox dropped the "F-bomb" for the second time in two days when discussing presidential front-runner Donald Trump's proposed border wall — this time, it was on live TV, CNN reports.